Abstract

Summary

Surveillance implies the study of a disappearing disease; the implementation of surveillance means a full coverage of the population under observation by case detection, both active and passive, identification of cases by microscopic examination and the epidemiological investigation of foci so that prompt remedial or preventive measures could be taken. Together with its own advantages, every method used in surveillance has limitations that should be reckoned with. When fully implemented, the surveillance methods have been found successful in many programs; conversely some failures have been recorded, particularly in tropical and subtropical countries where the potential for transmission is higher. Such setbacks are not due to the surveillance method per se but to the fact that the criteria for advancing from one phase to the next and upon which the decision regarding withdrawal of spraying was taken were either not observed or too strictly and indiscriminately followed irrespective of the epidemiological situation. These criteria, such as the annual parasite incidence, should be considered only as general guidelines, and judgment as to the termination of attack operations must be taken after adjusting these guidelines to the epidemiological factors having a bearing on the local epidemiological situation. One of the main factors is the malaria receptivity of the area which could be estimated by various methods.

Refinement of surveillance methods by the possible use of serological and electronic scanning procedures and reduction of costs of the eradication operations are fields of research that should be further explored.